This invention relates to an angle adjusting mechanism for an article support, and particularly a mechanism comprising a rotary member on the movable side which cooperates with a holding member on the fixed side, and they are freely rotatable and may be tightened together to be held at a desired relative rotation angle.
In one known possible use for the invention, the installation of an audio speaker on a ceiling, as shown in prior art FIG. 6 herein, for instance, the bearing rotary member 94 of a prior art installation bracket 93 of the speaker S are combined, so as to be freely tightened to the axial part 91 of the holding member 90 that is fixed to the ceiling. This holds the rotary member 94 at a desired rotation angle. A cut groove 95 is formed through the ring of the bearing rotary member 94 and the split ring at the cut groove 95 is loosened by rotation of an "eye bolt" 96 to loosen the member 94 for rotation and to then tighten the member 94 to maintain the fixed axial part 91 and member 94 at a desired angle, as shown by the dotted line in FIG. 6, thereby adjusting the installation angle of the speaker S.
In this conventional mechanism, however, the retention of the speaker S at the selected orientation is influenced by the gripping force of the bolt 96 tightened to bear the rotary member 94 against the axial part 91. As a result, it has been necessary to increase the size of the rotary members 91 and 94 where the load on the speaker side is excessively heavy. Also, where the angle of incline of the speakers is large, there is a further need to increase the size of the member 94 for increasing the gripping force, due to the larger torque that is generated on the member 94. However, there are restrictions that makes unacceptable increase in the size of the angle adjusting mechanism from the standpoints of the installation space and the external appearance in addition to the disadvantage of increased overall weight.